If you are designing a data warehouse, you need to map out all the areas where there is a potential for your project to fail, before you begin.
Lack of Documentation
Mistake 2: Creating haphazard metadata layer documentation
The metadata is the integrator between data processes extract, transform, load (ETL) and BI. Unfortunately, a problem arises when the metadata layer is designed solely to fit shortsighted data criteria, which results in haphazard documentation.
In order to avoid this mistake, you must add descriptions to the tables or columns at the data design stage itself. If a business user rejects a BI report, it's most likely because of a poorly designed data model that lacks an accessible description and uses inconsistent naming conventions. Prevent this by creating a metadata strategy at the data modeling stage of data warehouse design.